fiberglass repair

[fzar]

Anyone out there have recommendations and advice for fiberglass repair. I dropped my track prepped bike with fairings and damaged the fiberglass substantially on one side. The recommendations and advice along what repair materials I'll need, inside info, watch out for this or that, all recommendations and advice are greatly appreciated.

The tail section has been reordered.

[Evill_Ed]

I got ya covered Dave. Glasss repair is fairly easy.

First clean the inside and outside of the repair area with wax and grease remover 

You will start your repairs on the back side. Remove any loose pieces and grind around the repair area approximately 1-in on all sides.  Go to the front side and remove any loose pieces and try to realign the shape of  the part. Put a layer of metal duct tape over the damaged areas to hold them in place and to maintain the shape. The metal tape tape does a good job of holding a shape.

Cut a layer or 2 of fiberglass cloth the shape of the damaged area, the cloth should also be approximately an inch larger than the damage. Mix up an ounce or two of the resin with hardener. Lay the first layer of cloth over the hole. Pour a little of the resin on the cloth and carefully brush it into the cloth. I use acid brushes for this. As you wet the cloth it will turn from white to translucent. Use the brush to dab downwards on any air bubbles to work them out. You want a uniform appearance without any bubbles. Don't over work it,once it looks good, leave it alone. Let the resin cure, this takes approximately 15-20 Minutes. You can add a second layer with the same steps as before if you choose to, usually one layer is adequate. After it cures you can carefully peel off the aluminum tape on the front side. Grind around the edges of the repair area,  at least an inch, and then apply body filler. You can use fiberglass reinforced filler like dura glass for additional strength as your first layer or just use regular body filler to fill, shape and smooth.  I use 80 grit for initial sanding and shaping, followed by 180 grit to smooth and feather. You can then sand again with 320 grit and prime. 

 

Here are some pics of products and a modification I made to Dylan's belly pan to clear the header pipes. Again, I used the aluminum tape to form the shape, applied glass coth and resin on the back side and then finished the front with dura glass and then regular filler.

 

Let me know if you have any questions. 

Ed

 

[M. Hausknecht]

Great description Ed! Once you accumulate the stuff needed, its really pretty easy to get satisfactory results. You'll want graduated measuring cups to get the quantities right. Some folks favor using glass mat. I've found cloth to be easier to work with, lighter in weight, and plenty strong until the next repair is needed. You'll want a pint or quart of acetone for clean up and, oh yes, gloves to keep the resin off your fingers.

The prep is most important to the result, as Ed described. The tape on the outside, to assure you've got the shape you want, is crucial as the last step prior to wetting out the inside surface with resin and laying the cloth. You want to minimize the amount of filler you need; its heavy and adds no strength. Some folks rave about the West Marine repair kits.

WEST SYSTEM 105-K Fiberglass Boat Repair Kit | West Marine

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Personally, I prefer epoxy resin over polyester resin; it seems to end up a little tougher and more flexible before it cracks. I've gotten most of my supplies here https://www.fibreglast.com/.  After racing and crashing fiberglass bodied race cars and motorcycles for over 20 years, I have a selection of woven cloths, including kevlar for extra abrasion resistance, and resins with different pot lives. 

Sorry about your crash but the damage doesn't look too bad.

[fzar]

Thanks for the detailed response @Evill_Ed , man that's a detailed response.

Thanks to @M. Hausknecht for your additional advice and links.

Thanks a lot.

Dave.

[jb.junior]

On 5/10/2022 at 3:43 AM, Evill_Ed said:

I got ya covered Dave. Glasss repair is fairly easy.

First clean the inside and outside of the repair area with wax and grease remover 

You will start your repairs on the back side. Remove any loose pieces and grind around the repair area approximately 1-in on all sides.  Go to the front side and remove any loose pieces and try to realign the shape of  the part. Put a layer of metal duct tape over the damaged areas to hold them in place and to maintain the shape. The metal tape tape does a good job of holding a shape.

Cut a layer or 2 of fiberglass cloth the shape of the damaged area, the cloth should also be approximately an inch larger than the damage. Mix up an ounce or two of the resin with hardener. Lay the first layer of cloth over the hole. Pour a little of the resin on the cloth and carefully brush it into the cloth. I use acid brushes for this. As you wet the cloth it will turn from white to translucent. Use the brush to dab downwards on any air bubbles to work them out. You want a uniform appearance without any bubbles. Don't over work it,once it looks good, leave it alone. Let the resin cure, this takes approximately 15-20 Minutes. You can add a second layer with the same steps as before if you choose to, usually one layer is adequate. After it cures you can carefully peel off the aluminum tape on the front side. Grind around the edges of the repair area,  at least an inch, and then apply body filler. You can use fiberglass reinforced filler like dura glass for additional strength as your first layer or just use regular body filler to fill, shape and smooth.  I use 80 grit for initial sanding and shaping, followed by 180 grit to smooth and feather. You can then sand again with 320 grit and prime. 

 

Here are some pics of products and a modification I made to Dylan's belly pan to clear the header pipes. Again, I used the aluminum tape to form the shape, applied glass coth and resin on the back side and then finished the front with dura glass and then regular filler.

 

Let me know if you have any questions. 

Ed

 

Badass write-up.